Frequency and Temperature Interactive Effects on Hot Mix Permanent Deformation Using Response Surface Methodology

Abstract

Effects of two of the most important factors influencing permanent deformation of styrene–butadiene–styrene (SBS)-modified and unmodified asphalt—frequency and temperature as well as their interactive effects—are studied using dynamic creep test. The authors used a sophisticated experimental design method known as central composite design (CCD) that provides a continuous mathematical equation for the response (permanent deformation, in this study) based on the independent factors as well as their interactions. Using this design method enhances the statistical validation of laboratory results based on the least-required test. Dynamic creep tests were conducted at three levels of temperature (